>nobody would think it's ok if I charge Joe $5, but charge Bob $10 because I don't like him very much
Are you sure? People often cheer on this kind of thing if they also think Bob's an asshole. (And there's no rule against it in most places unless you don't like Bob for fairly specific reasons)
People will often cheer on all kinds of disgusting behavior including torture. Our laws should help to discourage the base instincts we haven't grown out of and make our lives more fair and reasonable than it would be if we left things to the whims of angry mobs, robber barons, and bigots
Are you sure? People often cheer on this kind of thing if they also think Bob's an asshole. (And there's no rule against it in most places unless you don't like Bob for fairly specific reasons)